Dehydrated culture media
Gelatin Lactose Medium
For the confirmation of Clostridium perfringens.
- Cat. No.
- LC-1526
- Category
- Dehydrated culture media
- Format
- 500 g
- Storage
- 2 to 25 °C
- Minimum guaranteed shelf life
- 15 months
Gelatin Lactose Medium is used to determine the identity of presumptive Clostridium perfringens. It contains lactose to test lactose fermentation and gelatin to test liquefaction.
Key features
Applications
Confirmation of Clostridium perfringens.
Industry
Food, water.
Preparation
155 g in one liter of distilled water; boil for one minute, dispense and sterilize in autoclave at 121 °C for 15 minutes.
Principles and uses
The lactose fermentation is indicated by the presence of gas bubbles as well as a color change of the medium from red to yellow. Gelatin is a protein derived by the hydrolysis of collagen, and is found abundantly in bones, skin, tendons, cartilage and animal tissue. It is used in culture media to determine gelatinolysis by bacteria; the gelatinases produced by the microorganisms hydrolyze the gelatin, liquefying a solid medium. Tryptose provides nitrogen, vitamins, minerals and amino acids essential for growth. Yeast extract is a source of vitamins, particularly of the B-group. Lactose is the fermentable carbohydrate, producing acid indicated by the phenol red indicator. Phenol red changes to yellow when acid is produced and to red when an alkalinisation of the medium is produced. Cracks or bubbles in the medium indicate gas production.
Technical specifications
| Solubility | Without residues |
|---|---|
| Appearance | Fine powder |
| Color of the dehydrated medium | Red |
| Color of the prepared medium | Dark red |
| Final pH (25 °C) | 7.5 ± 0.2 |
| Amount per litre | 155 g |
| Storage | 2 to 25 °C |
Formula
| Ingredient | g/L |
|---|---|
| Gelatin | 120 |
| Lactose | 10 |
| Phenol red | 0.05 |
| Tryptose | 15 |
| Yeast extract | 10 |
Preparation and use
Preparation
Suspend 155 grams of the medium in one liter of distilled water. Mix well and dissolve by heating with frequent agitation. Boil for one minute until complete dissolution. Dispense into appropriate containers and sterilize in autoclave at 121 °C for 15 minutes.
Instructions for use
- Inoculate and incubate at 35 ± 2 °C for 24-48 hours.
- To read gelatinase, refrigerate until well chilled and compare to non-inoculated tubes. Tubes positive for gelatinase will remain liquid. C. perfringens usually liquefies the gelatin after 24-44 hours.
- The isolated colonies which are not motile, reduce nitrate, ferment lactose and produce liquefaction of gelatin in 48 hours are presumptively identified as Clostridium perfringens.
Note: not all Clostridium perfringens strains reduce nitrate to nitrite.
Quality control
Microbiological test
Incubation conditions: 35 ± 2 °C / 24-48 h.
| Microorganism | Specification | Characteristic reaction |
|---|---|---|
| Clostridium sporogenesATCC 11437 | Good growth | Gelatinase (+) |
| Clostridium perfringensATCC 13124 | Good growth | Gelatinase (+). Color change to yellow. |
Bibliography
- APHA. 3rd Edition Compendium of methods for the microbiological examination of foods.
- Métodos Analíticos del Laboratorio del Instituto Nacional del Consumo (CICC). Alimento I Ministerio de Sanidad y Consumo 1999.
- Department of Health NHS Executive: The Caldicott Committee. Report on the review of patient-identifiable information. London. December 1997.
What you receive
The product
Shipped under controlled temperature when the product requires it.
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